1. Field of the Invention
This invention relates broadly to surgical devices. More particularly, this invention relates to orthopedic implants, and specifically to bone plates and drill guides.
2. State of the Art
Fracture to the metaphysis of a long bone can be difficult to treat. Improper treatment can result in deformity and long-term discomfort.
By way of example, a Colles' fracture is a fracture resulting from compressive forces being placed on the distal radius, and which causes backward or dorsal displacement of the distal fragment and radial deviation of the hand at the wrist. Often, a Colles' fracture will result in multiple bone fragments which are movable and out of alignment relative to each other. If not properly treated, such fractures may result in permanent wrist deformity and limited articulation of the wrist. It is therefore important to align the fracture and fixate the bones relative to each other so that proper healing may occur.
Alignment and fixation of a metaphyseal fracture are typically performed by one of several methods: casting, external fixation, pinning, and plating. Casting is non-invasive, but may not be able to maintain alignment of the fracture where many bone fragments exist. Therefore, as an alternative, external fixators may be used. External fixators utilize a method known as ligamentotaxis, which provides distraction forces across the joint and permits the fracture to be aligned based upon the tension placed on the surrounding ligaments. However, while external fixators can maintain the position of the wrist bones, it may nevertheless be difficult in certain fractures to first provide the bones in proper alignment. In addition, external fixators are often not suitable for fractures resulting in multiple bone fragments. Pinning with K-wires (Kirschner wires) is an invasive procedure whereby pins are positioned into the various fragments. This is a difficult and time consuming procedure that provides limited fixation if the bone is comminuted or osteoporotic.
Plating utilizes a stabilizing metal plate typically placed against the bone, fixed-angle pegs (which may have threaded or non-threaded shafts) positioned through the plate and entering drilled holes adjacent an articular bone surface, and cortical screws extending from the plate into holes drilled in the bone to provide stabilized fracture fixation. For example, co-owned U.S. Ser. No. 10/664,371, which is hereby incorporated by reference herein in its entirety, discloses a plate particularly adapted to treat dorsally displaced metaphyseal fractures from the volar side of the wrist.
When fixed-angle pegs are utilized in conjunction with a bone plate, it is necessary to ensure that the pilot holes drilled for the pegs are co-axial with the hole axes. Otherwise, the shaft of the pegs will not properly align with the anatomy, and the head of the pegs will not properly align with the threaded holes of the plate, potentially resulting in cross-threading. As a result, with the plate placed upon the bone, prior to drilling each hole in the bone in alignment with a peg hole, a drill guide is attached to the plate at the peg hole. The guide defines a tubular passage which directs the drill bit in the proper orientation for a peg through the particular peg hole. After drilling each hole, the drill guide is removed, the peg is inserted in the peg hole, and the drill guide is coupled to a subsequent peg hole.
The process of attaching the drill guide during the surgical procedure is laborious. It can be difficult to locate the appropriate angle for threadably coupling the guide to the peg hole during the procedure, given that each peg hole may have a discrete axis angle from the other peg holes. Such difficulty can unnecessarily prolong the surgical procedure.